Temporal changes in PTEN and mTORC2 regulation of hematopoietic stem cell self-renewal and leukemia suppression

Cell Stem Cell. 2012 Sep 7;11(3):415-28. doi: 10.1016/j.stem.2012.05.026.

Abstract

Pten deletion from adult mouse hematopoietic cells activates the PI3-kinase pathway, inducing hematopoietic stem cell (HSC) proliferation, HSC depletion, and leukemogenesis. Pten is also mutated in human leukemias, but rarely in early childhood leukemias. We hypothesized that this reflects developmental changes in PI3-kinase pathway regulation. Here we show that Rictor deletion prevents leukemogenesis and HSC depletion after Pten deletion in adult mice, implicating mTORC2 activation in these processes. However, Rictor deletion had little effect on the function of normal HSCs. Moreover, Pten deletion from neonatal HSCs did not activate the PI3-kinase pathway or promote HSC proliferation, HSC depletion, or leukemogenesis. Pten is therefore required in adult, but not neonatal, HSCs to negatively regulate mTORC2 signaling. This demonstrates that some critical tumor suppressor mechanisms in adult cells are not required by neonatal cells. Developmental changes in key signaling pathways therefore confer temporal changes upon stem cell self-renewal and tumor suppressor mechanisms.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aging / pathology
  • Animals
  • Animals, Newborn
  • Carrier Proteins / metabolism
  • Cell Proliferation
  • Enzyme Activation
  • Gene Deletion
  • Hematopoietic Stem Cell Mobilization
  • Hematopoietic Stem Cell Transplantation
  • Hematopoietic Stem Cells / enzymology*
  • Hematopoietic Stem Cells / pathology*
  • Humans
  • Leukemia / enzymology
  • Leukemia / pathology*
  • Leukemia / prevention & control*
  • Mechanistic Target of Rapamycin Complex 2
  • Mice
  • Mice, Inbred C57BL
  • Multiprotein Complexes / metabolism*
  • PTEN Phosphohydrolase / metabolism*
  • Phosphatidylinositol 3-Kinases / metabolism
  • Phosphorylation
  • Proto-Oncogene Proteins c-akt / metabolism
  • Rapamycin-Insensitive Companion of mTOR Protein
  • Signal Transduction
  • TOR Serine-Threonine Kinases / metabolism*
  • Time Factors
  • Tumor Suppressor Protein p53 / metabolism

Substances

  • Carrier Proteins
  • Multiprotein Complexes
  • Rapamycin-Insensitive Companion of mTOR Protein
  • Tumor Suppressor Protein p53
  • rictor protein, mouse
  • Phosphatidylinositol 3-Kinases
  • TOR Serine-Threonine Kinases
  • Mechanistic Target of Rapamycin Complex 2
  • Proto-Oncogene Proteins c-akt
  • PTEN Phosphohydrolase
  • Pten protein, mouse